The present invention generally relates to UV curable coatings and more specifically to UV-curable coatings having improved oil and grease resistance that are particularly suited, without limitation, to packaging materials.
Fluorochemicals as coatings or finishes for paper substrates generally exhibit three useful characteristics, namely, water repellency, oil and grease repellency and soil resistance. Emphasis can be placed on selected ones of these features by changing the chemistry in the fluorochemical used. However, when the amount of one property is increased, there usually is a corresponding reduction in emphasis on the other properties. Therefore, fluorochemicals are not a single product but a family of products designed for specific end-uses. Heretofore, fluorochemicals were thought to be the only finishing treatment that provides the optimum balance of these three characteristics to suit the end-use.
3M is a well-known manufacturer in the fluorochemical coating industry. Recently, 3M announced it is phasing out of some fluorine-related chemistry used to produce certain repellents and surfactant products. The affected product lines represent about two percent of 3M""s nearly $16 billion in annual sales. More specifically, these products include a popular line of coatings used for oil and grease resistance on paper packaging, such as, for example, pet food bags and paper cartons.
While this chemistry has been used effectively for more than 40 years and the products generally are regarded as safe, the decision to phase out production is based on principles of responsible environmental management. Sophisticated testing capabilities, some developed in only the last few years, show that persistent by-product compounds from the fluorochemicals can be detected in the environment and in people.
With the imposition of environmental and health risks and the phase-out of 3M products, alternatives to fluorochemicals, especially in the field of coatings used for oil and grease resistance on paper packaging, are needed.
According to the present invention the varnish, which was conventionally applied over the previous fluoropolymer, now has a non-flourinated, oil and grease resistant additive, preferably a chlorinated paraffin incorporated therein. The chlorinated paraffin serves as an oil and grease resistant agent in the varnish coating for paper packaging materials. The chlorinated paraffin provides oil and grease resistance while maintaining an appropriate viscosity for the composition.
Thus the present invention is an improved over print varnish (OPV) and a paper and paperboard packaging treatment that provides oil and grease resistant properties. Preferably, the composition is used to treat the surface of a paper substrate, the substrate being used in the manufacture of packaging materials containing oily and greasy products, for example pet food bags.
Another aspect of the invention is an oil and grease resistant composition primarily made up of a chlorinated paraffin solubalized in a varnish.
These and other aspects of the present invention as disclosed herein will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments. The description is for the purpose of describing a preferred embodiment of the invention and is not intended to limit the present invention.